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Proteins: Multipurpose Molecules in our Bodies!

Discover the diverse functions and structures of proteins, from enzymes to receptors, as well as the importance of their unique shapes. Learn about the primary, secondary, tertiary, and quaternary structures of proteins and the factors that can denature them.

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Proteins: Multipurpose Molecules in our Bodies!

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  1. Proteins

  2. Proteins Multipurposemolecules

  3. Where is protein in our bodies? • Hair • Blood • Enzymes

  4. Proteins • Most structurally & functionally diverse group of biomolecules • Function: • involved in almost everything • enzymes (pepsin, polymerase, etc.) • structure (keratin, collagen) • carriers & transport (membrane channels) • receptors & binding (defense: antibodies) • contraction (actin & myosin) • signaling (hormones: insulin) • storage (bean seed proteins)

  5. Proteins • Structure: • monomer =amino acids • 20 different amino acids • polymer =polypeptide • protein can be one or more polypeptide chains folded & bonded together • large & complex molecules • complex 3-D shape hemoglobin growthhormones Rubisco

  6. H O | —C— | H || C—OH —N— H Amino acids • Structure: • central carbon • amino group • carboxyl group (acid) • R group (side chain) • variable group • confers unique chemical properties of the amino acid R

  7. peptidebond Building proteins • Peptide bonds • linking NH2 of one amino acid to COOH of another • C–N bond dehydration synthesis

  8. Protein models • Protein structure visualized by • X-ray crystallography • extrapolating from amino acid sequence • computer modelling lysozyme

  9. hemoglobin collagen Protein structure & function • Function depends on structure • 3-D structure • twisted, folded, coiled into unique shape pepsin

  10. Primary (1°) structure • Order of amino acids in chain • amino acid sequence determined by gene (DNA) • slight change in amino acid sequence can affect protein’s structure & it’s function • even just one amino acid change can make all the difference! lysozyme: enzyme in tears & mucus that kills bacteria

  11. Sickle cell anemia

  12. Secondary (2°) structure • “Local folding” • folding along short sections of polypeptide • interaction between adjacent amino acids • H bonds between R groups • -helix • -pleated sheet

  13. “Let’s go to the video tape!” (play movie here) Secondary (2°) structure

  14. Tertiary (3°) structure • “Whole molecule folding” • determined by interactions between R groups • hydrophobic interactions • effect of water in cell • anchored by disulfide bridges(H & ionic bonds)

  15. Quaternary (4°) structure • More than one polypeptide chainjoined together • only then is it a functional protein • hydrophobic interactions collagen = skin & tendons hemoglobin

  16. Denature a protein • Unfolding a protein • disrupt 3° structure • pH salt temperature • unravels or denatures protein • disrupts H bonds, ionic bonds & disulfide bridges • destroys functionality • Some proteins can return to their functional shape after denaturation, many cannot In Biology,size doesn’t matter, SHAPE matters!

  17. multiplepolypeptides hydrophobic interactions aa sequence peptide bonds determinedby DNA R groups H bonds Protein structure (review) R groups hydrophobic interactions, disulfide bridges 3° 1° 2° 4°

  18. Let’s build some Proteins!

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